This invention relates to a watercraft and more particularly to an improved four cycle engine for the watercraft and auxiliaries for such engines.
There is a very popular type of small watercraft that is designated as a "personal" watercraft. This type of watercraft is quite compact in nature and frequently accommodates the operator and/or passengers seated in a straddle fashion. Where more than one occupant is present, the occupants frequently ride in a tandem fashion.
It has been generally the practice to employ as prime movers for such watercraft two-cycle engines. Two-cycle engines have a number of advantages, the prime of which is the relatively compact construction of such engines. In addition, with crankcase compression two-cycle engines, the induction and exhaust systems can be positioned relatively low on the engine and thus the engine can be quite compact in configuration.
This compact configuration is particularly important when the engine is disposed so that it is positioned beneath the seat of the watercraft. Using the tandem straddle-type seat arrangement, the seat is relatively narrow and tapers outwardly in a downward direction. Hence, two-cycle engines are particularly adapted for positioning beneath such seats.
There are, however, certain reasons why four-cycle engines may be more advantageous for use in such watercraft. Four-cycle engines may, in some instances, be more environmentally friendly and thus they are being considered for this type of application.
There are, however, certain difficulties with using four-cycle engines in watercraft and particularly small personal-type watercraft. The first of these is that the four-cycle engine is generally more complex and larger for a given output than a two-cycle engine. Since this type of watercraft is quite small, the positioning of the engine and all of its auxiliaries in a small watercraft can present some difficulties.
Also, because of the fact that four-cycle engines are lubricated by a lubricant source with the lubricant being recycled, the engine tends to become higher than a two-cycle engine, particularly if the crankcase is used as the reservoir for the lubricant. This can place the axis of rotation of the engine output shaft at a high enough level that a transmission or offset drive must be employed for driving the propulsion device for the watercraft.
On the other hand, if a dry sump lubricating system is employed, the engine can be mounted lower, but then there is a problem in the location of the dry sump tank for the engine, again due to the compact nature of the watercraft. In addition, because these watercraft are very sporting in their nature, the lubricating tank should be quite close to the engine so that if the watercraft becomes partially or totally capsized, the lubricant can return to its normal level in both the engine and in the dry sump tank once the watercraft is again righted.
It is, therefore, a principal object of this invention to provide an improved watercraft having a four-cycle internal combustion engine employing a dry sump arrangement.
It is a further object of this invention to provide a dry sump lubricating system for a four-cycle engine for a watercraft when the lubricant tank is mounted close to the engine.
Because of the sporting nature of this type of watercraft, as aforenoted, the watercraft frequently can become partially or fully capsized. This means that water is likely to enter into the engine compartment. If this water is allowed to come into contact with the air inlet system for the engine, the water can in fact enter the cylinders of the engine through the induction system. This problem may be further aggravated when the watercraft is again righted. Any water which may enter into the induction system can then flow by gravity into the engine through the induction system when the watercraft is again righted.
In addition, it is frequently the practice to discharge the exhaust gases from the engine, either into the body of water in which the watercraft is operating below the water level, or at a point close to the water level. Thus, water can enter the exhaust system under extreme conditions.
It has been the practice to employ water trap devices in the exhaust system which will permit the free flow of exhaust gases to the discharge, but which will trap water that may tend to enter the exhaust system if the watercraft is stationary and/or becomes partially or totally capsized. These water trap devices are, for the most part, quite effective.
However, with most watercraft engine exhaust systems, coolant from the engine is discharged into the exhaust system at some point upstream of the discharge end of the exhaust system. This water itself can escape the water trap device and may flow into the engine through the exhaust system when the watercraft is partially or totally capsized and subsequently righted.
It is, therefore, a still further object of this invention to provide an improved engine for a watercraft having an induction and an exhaust system, and wherein water is precluded from entering the engine through one or both of the systems.
It is a further object of this invention to provide an improved valving arrangement for a four cycle internal combustion engine designed for watercraft use that is positioned close to the engine cylinders and which will preclude water from entering the cylinders through the intake and/or exhaust systems.
It should be readily apparent from the foregoing description that watercraft of the type disclosed operate with the engine exposed to a fairly substantial amount of water. This water can be drawn into the engine through the induction system during the time when the engine is running and/or if the engine is not running and the watercraft becomes partially or totally capsized and is again righted.
It is, therefore a still further object of this invention to provide an improved air inlet device for a watercraft engine that will preclude the likelihood of water entering the engine through the induction system.
It is a further object of this invention to provide an improved air inlet device for a watercraft engine wherein water, which may be mixed with the air inducted, can be separated in the inlet device.